Preparation of drying oils



Patented Jan. 1, 1952 2,581,094 PREPARATION OF DRYING OILS Anthony H.Gleason,

Westfleld, and Stanley E.

Jaros, Rahway, N. J assignors to Standai 6 Oil Development Company, acorporation of Delaware No Drawing. Application September 29, 1948,Serial No. 51,867

9 Claims.

This invention relates to synthetic drying oils and more particularlyrelates to the manufacture of oily linear polymers by the bulkpolymerization of a diolefin or a mixture of a diolefin with a vinylcompound at a relatively low temperature and in the presence of aperoxide catalyst.

It is known to prepare oily products by polymerizing diolefins such asbutadiene, its homologs, or mixtures of diolefins with vinyl compounds.Serial No. 782,850, filed October 29, 1947,

in the name of Erving Arundale. Anthony H.

Gleason, and Fred W. Banes, describes and claims a particularlyeflicient method for preparing such oils by polymerizing dioleflns or adiolefin and a vinyl compound under 3 to atmospheres pressure at atemperature not over 150 C. for a period of time between 3 and hours inthe presence of a peroxide catalyst and a diluent which may or may notbe inert with respect to the polymerization process. The product of thisprocess has a molecular weight between 2000 and 5000 and is particularlyuseful as a drying oil.

The above process, however, has the disadvantage that considerableamounts of insoluble solid and/0r gel-like polymer are formed on thereactor walls, particularly in the vapor space. In commercial operationthe formation of such polymer would be accelerated and would offer thehazard of plugging up the lines and reducing yields.

It is therefore the main object of this invention to provide a method ofovercoming or at least considerably reducing the formation of thisundesirable insoluble polymer.

The objects of this inventionare accomplished by continually contactingthe vapor space surfaces of the reactor with a portion of the liquidphase in the reactor. This may be accomplished in any desired manner. Inbatch operation in a bomb, the bomb may simply be shaken to ensure aconstant supply of liquid phase on the walls of the reactor. In largescale equipment, and in particular, in continuous operation a portion ofthe liquid phase may be pumped to the top of the reactor and allowed tocascade down the walls.

By the principles of the present invention, oily diolefin polymers orcopolymers can be produced in bulk by the use of a peroxide catalystunder such conditions that about 35 to of the.

monomer charge is converted into the desired drying oil. This method isunusually flexible in that the molecular weight of these oily polymerscan be most advantageously and accurately controlled within a wide rangeof predetermined limits below those of rubbery polymers by the properselection of a diluent and/or other modiher, by adjusting the catalystconcentration of the feed and by keeping the conversion below 70%.

In practicing this invention a polymerizable diolefin or a mixture ofdiolefins, or a mixture containing a diolefin and a polymerizablecoreactant containing a single C=C group, a catalytic amount of aperoxide type catalyst, and a diluent with or without otherpolymerization modifiers, are charged into a pressure vessel and thevessel is then maintained at a superatmospheric pressure of about 3 to20 or 30 atmospheres and at a temperature not in excess of 150 0.,preferably between and C. The usual reaction period for such apolymerization has been found to be between 3 and 25 or even 60 hours,depending primarily on the catalyst concentration.

The product, an oily polymer or a solution of the polymer having amolecular weight preferably between 2000 and 5000, is then removed fromthe pressure vessel and the unreacted monomers are allowed to volatilizeor are removed by distillation. When desired the viscosity of theproduct may be cut back by a diluent, adding, for instance, up to equalparts by volume of an inert solvent such as benzol, xylene, solventnaphtha, a petroleum hydrocarbon fraction boiling in the range of aboutC. to 200 C. or other solvents suitable for diluting linear polymers ofoily character. In general, for the most practical manner ofapplication, these diluted drying oils should preferably have aviscosity of between about 1 and 3 poises at 50% N. V. M. (non-volatilematter) although a range of 0.5 to 10 or 15 is usable for specificpurposes.

Conversely, if a very large amount of diluent was present during thepolymerization reaction, it may be desirable to evaporate a portion orall of the diluent at the end of the polymerization period, oreventually replace the original diluent by another one. If the productis to be used as a protective film-forming coating, solvents boilingbetween about 100 to 200 C. are usually preferred, while solventsoutside of this range may be useful if the product is intended for otheruses, for example in printing ink formulations 'or for adhesives. Usualdrying oils of natural origin and/or resins known in the coating art mayalso be added tothe product, but such addition has not been foundnecessary because the drying oils themselves possess such excellentproperties that such additional ingredients are 55 of little benefit.

In preparing the drying oils according to this invention, butadiene-l,3is the preferred polymerizable raw material. Other useful polymerizablematerials are isoprene, piperylene, the dimethyl-butadienes andmethylpentadienes, dicyclopentadiene, chloroprene, bromoprene, mixturesof any of the aforementioned dioleflns, and generally all dioleilnshaving from 4 to 6 carbon atoms per molecule.

Instead of polymerizing the dioleflnic monomers alone, it is possible touse mixtures of .diolefins with monooleilns or polymerizable compoundscontaining a single C=C group, such as ethyl fumarate. ethyl maleate,methyl acrylate, methyl methacrylate, acrylonitrile, methacrylonltrile,vinyl acetate, vinyl chloride, vinylidene chloride, trichloroethylene,vinyl isobutyl ether, styrene, methyl styrene, para-methyl styrene, allmonoand di-chloro-styrenes, chloromaleic anhydride, and the like. Thevinyl compounds are preferably present in minor proportions, e. g., toby weight of the total polymerizable mixture. In general, the presenceof the above mentioned vinyl compounds in the. monomeric mixture tendsto accelerate the polymerization rate, especially in the case ofacrylonitrile, styrene, or methylmethacrylate.

Another benefit obtained by polymerizing mixtures containing the abovementioned monooleflnic compounds is the lower unsaturation of thecopolymerized product and hence improved aging properties, while thesomewhat reduced drying rate can be brought up to the desired standardsby incorporation of driers in the oil. Furthermore, especially in thecase of acrylonitrile copolymers, the soap and caustic resistance offilms resulting therefrom was found to be superior to the reistance ofcomparable dioleflnic homo-polymers, this advantage being somewhatbalanced by a darker coloration of the product and by the increasedcomplexity of the apparatus necessary for recovering unreacted monomersfrom the polymerization. At any rate. it will be seen from the foregoingdescription that by a judicious selection of monomers a wide variety ofproducts can be obtained by the present process, the character of theproducts being susceptible of still further control or modification by aproper variation of additional factors mentioned below.

In order to obtain economical yields of the desired oily polymers of thepreferred molecular weight, it has been found that the polymerization isbest conducted at moderate temperatures, for instance, between 75 and140 C., using a peroxide type catalyst. In particular, we have foundthat cumene hydroperoxide having the formula is unusually effective incatalyzing the reaction. This hydroperoxide may be used either in itschemically pure form or may equally well be in the form of therelatively inexpensive commercial mixture containing, for instance, 50to 60 wt. per cent of cumene hydroperoxide and 50 to 40 wt. per cent ofunconverted, inert cumene plus other components.

The useful range of concentration of peroxide typecatalysts generallycan be defined for the purposes of the present invention as beingbeingredient based on the monomer. preferably between 1 and 1.5 mol percent.

Besides cumene hydroperoxide, catalyst which possess a similarlyoutstanding effectiveness in the process of our invention includet-butyl hydroperoxide, ortho-, meta-, or para-cymene hydroperoxide,t-butyl perbenzoate and cumene perbenzoate. All of these compounds canbe represented by the general formula CH: a-o-o-o-w wherein R isselected from the group consisting of methyl, phenyl and tolyl andwherein R is selected from the group consisting of hydrogen and benzoyl.Hence it will be seen that our preferred catalysts are characterized byhaving the -O0-- group linked to a tertiary carbon atom and furthercharacterized by the total absence of secondary hydrogen atoms from themolecule.

However, other peroxides which are hydrocarbon soluble, such as acetylperoxide, benzoyl peroxide, t-amyl hydroperoxide or pcrbenzoate, and thelike, are also useful, though being only about one-half as effective ona molar basis as the aforementioned preferred compounds.

The preferred diluents for use in the present invention are butane,xylene, benzol, toluene, cyclohexane, solvent naphtha, or a petroleumhydrocarbon fraction boiling between -15 C. and 200 C., or generallynon-olefinic hydrocarbon solvents boiling between -15 C. and 200 C. Onthe other hand, solvents such as carbon tetrachloride, chloroform,halogenated hydrocarbons boiling between 60 and 200 C. generally, andoleflnic solvents may be also used but are not inert toward thereaction. The halogenated solvents may sometimes be preferred over theinert ones because they exert a modifying eil'ect on the polymerizationreaction without seriously affecting the reaction rate, but isobutyleneand the normal butenes lower the catalyst efliciency and tend to resultin low conversions.

The viscosity of the product can be controlled by adding to themonomeric polymerization mixture, 0.3 to 5 weight percent of diisopropylxanthogen disulflde (hereinafter also referred to as DXD) which ispreferred for this purpose because it is outstanding in that it does notaffect the reaction rate appreciably. Among other modifiers useful inthe present process, flowers of sulfur (which probably are convertedinto other compounds during the course of the polymerization) have alsobeen found quite effective in keepin the viscosity of the polymericproduct in the preferred range between 1 and 5 poises, but this use ofsulfur can be disadvantageous because of the malodorcus by-productsformed.

Still another effective modifier is carbon tetrachloride which can beused in amounts as high as by volume of the polymerizable material andwhich in addition to its normal effect as a diluent can influence thepolymerization by playing a more vigorous role in the mechanism ofactive chain transfer and/or termination.

The following specific examples are still further descriptive of thepresent invention which gives excellent yields of linear, water-whiteoily polymers in an economical manner, with only about 0.1 to 4 wt.percent of the diolefln charge going to dimer. No treatment is requiredto improve the color or odor of the resulting products, which are highlysatisfactory, dry well and form tween 0.3 and 3 mol percent of activecatalyst 1. superior varnish-like finishes when baked or air dried. Itwill be understood that these examples are presented only asillustrations and not as limitations oi the invention. I

Example I 100 parts by weight of butadiene, an equal volume (123 partsby weight) of a petroleum diluent having a boiling range of 150-200" C.and 8.5

parts by weight of commercial cumene hydroperoxide (50% purity) werecharged to a stainless steel reactor and heated in a quiescent conditionunder self-generated pressure for 15 hours I at 100 C. The maximumpressure was about Example II The process of Example I was repeatedwhile shaking the bomb horizontally so as to continually supply theliquid phase to the walls of the reactorabove the normal surface of theliquid. After 110 hours operation or the equivalent of five runs, theamount of solid, insoluble polymer found on the walls of the bombamounted to only 0.5% by. weight of the total butadiene charged and wasequally distributed between the portions of the walls lying above andbelow the normal surface of the liquid in the bomb. Therefore, over aperid of five runs, wall-wetting resulted in the formation of only 22%of the normal amount of popcorn polymer 'or a reduction of 78%. Fiveruns appeared to be the optimum for comparative purposes since largeraccumulations of insoluble polymer were likely to be partially sloughedduring agitation.

, on adding 0.3% lead naphthenate and 0.03% (by weight) of manganesenaphthenate as driers to the oily product. films of 0 to 1.0 milthickness, prepared by dipping a thin metal sheet into the oil, dried inair dust-free in 4 hours, the dried films being characterized by a highgloss. Films baked for one hour at 125 C. in the absence of any drierpossessed superior flexibility, adhesion, and hardness and were found tobe very resistant to water, soap and grease. Alkali resistance was fair.Air-dried films, after 48 hours, were slightly inferior to the bakedcoatings, but generally good except for resistance to alkali.

Fa-dometer tests at 140 F. for 300 hours re- However, in the vaporspace, where the concentration-of butadiene is high, insoluble polymerforms rapidly on the walls of the reactor. This formation is apparentlyautocatalytic and its rate'accelerates logarithmically. Furthermore,

1 the insoluble polymer does not leave the reactor with the product andthusaccumulates so that reactor must be opened at relatively frequentintervals for costly and hazardous manual clean ing.

Ordinary methods of inhibiting the formation of the insoluble polymer onthe walls in the vapor space, such as treatment with nitrites or organicinhibitors, are not effective because peroxides are used as catalyst andquickly destroy the inhibitors.

From the above examples it is evident that this invention effectivelycombats the insoluble polymer problem by leaving no vapor space havinghigh concentration of diolefin in contact with the wall and thus greatlyreducing rate of insoluble polymer formation. The flushing operation, inaddition to reducing rate of insoluble polymer formation. also has thefunction of washing down a major portion of the polymer that does form rso that it can be carried out of the reactor with the product andsubsequently filtered out.

The nature and objects of the present invention having been thus fullyset forth and specific examples of the same given, what is claimed asnew and useful and desired to be secured by Letters Patent is:

1. In a selective polymerization process for preparing drying oilswherein a conjugated diolefin having 4 to 6 carbon atoms per molleculeis heated in the liquid phase in a reaction zone at a temperaturebetween and 150 C., under suvealed no visible checkin or other sign ofdeteri-" oration of either the air-dried or baked films, except for aslight yellowing.

. In view of the exceptionally favorable properties of the clear filmsobtained upon drying the oily products of this invention, the productsare particularly suitable as vehicles for paints and enamels to whichany desired color may be imparted by admixing an appropriate pigmenttherewith. Conventional driers such as compoundsof lead, manganese orcobalt may also be added to accelerate the rate of drying in air, butaddition of such driers is usually unnecessary in the case of bakedenamels. In general, enamels prepared from our product dry in air toform films with excellent gloss and color, satisfactory flexibility andstrong adhesiveness. The films peratmospheric-pressure and in thepresence of a hydrocarbon soluble peroxide catalyst for a periodsufiicient to convert not more than of the diolefin into a linear oilypolymer and not more than 5% into a diolefin dimer, the method ofreducing the formation of solid insoluble polymer which comprisescontinually flushing the entire interior surfaces of the gas space abovethe liquid level of the reaction zone with at least a portion of theliquid phase.

2. A process according to claim 1 wherein 1 volume of diolefin ispolymerized in the presence of A, to 5 volumes of a diluent boilingbetween l5 C. and 200 C.

3. In a process for preparing drying oils by heating butadiene-1,3 inthe liquid phase at a temperature between 50 and C. in a closed reactionzone under its autogenous pressure in the presence of 0.3 to 2 mol percent per mol of butadiene of a catalyst having the formula R- O0Rwherein R is a member selected from the group consisting of methyl andphenyl and R is a member selected from the group consisting of hydrogenand benzoyl, continuing the heating until a linear oily polymer having.a molecular weight between 1000 and 10,000 is formed the improvementwhich comprises simultaneously continuously flushing the entire interiorsurfaces of the gas space above the liquid level of the reac tion zonewith at least a portion of the liquid phase. 1

4. A process according to claim 3 wherein the catalyst is cumenehydropercxide.

5. A process according to claim 3 wherein the catalyst is t-butylhydroperoxide.

6. A process according to claim 3 wherein 0.3 to 5 weight per cent basedon butadiene of diisopropyl xanthogen disultlde is added to thepolymerizable charge.

7. In a process for preparing drying oils by mixing '70 to 95 parts byweight of a conjugated diolefin having 4 to 6 carbon atoms per moleculeand 30 to 5 parts by weight of a copolymerizable compound having asingle -C=C- group, heating the resulting mixture in the liquid phase ina reaction zorie at a temperature between 50 and 150 C. and at apressure ranging from 3 to 30 atmospheres in the presence of 0.3 to 3mol per cent per total monomer of a catalyst having the formula whereinR is a radical selected from the group consisting of methyl and phenyland wherein R is a radical selected from hydrogen and benzoyl, therebyforming a water-white linear oily cpolymer having a molecule weightbetween 1000 and 10,000, the improvement which comprises simultaneouslycontinually flushing the entire interior surfaces of the gas space abovethe liquid level of the reaction zone with at least a portion of theliquid phase.

8. In a process for selectively converting diolefins into unsaturatedoily polymers by heating one volume of liquid butadiene monomer with to5 volumes of a hydrocarbon diluent boiling between 80 and 200 C., and 1to 7 weight percent of cumene hydroperoxide based on monomer, heatingthe mixture for 3 to 60 hours in the liquid phase in a closed reactionzone at a temperature between 80 .and 125 C. at the autogenous pressure,whereby a major proportion of monomer is converted into a hydrocarbonsoluble drying oil and only between 0.1 and 5% by weight 0! monomer isconverted into dimer and 0 to 0.5% into insoluble polymer, releasingpressure from the reaction zone, stripping unpolymerized mon omer fromthe polymerized reaction mixture, tractionating the stripped mixture toremove the dimer and excess hydrocarbon diluent therefrom, andrecovering a solution of said drying oil in said hydrocarbon diluent,the improvement which comprises continually flushing the entire interiorsurfaces or the gas space above the liquid level of the reaction zonewith at least a portion of the liquid phase.

9. In a selective process for the production of a synthetic drying oilby mixing '70 to parts by weight of butadiene, 30 to 5 parts by weightof styrene, 20 to parts by weight of an inert. non-olefinic hydrocarbondiluent boiling between 80 and 200 C. and 2.5 to 7 parts by weight ofcumene hydroperoxide, heating the resulting mixture for 3 to 25 hours inthe liquid phase in a closed reaction zone at a temperature between 80and C. at a pressure of 3 to 20 atmospheres, whereby 35 to 70% by weightof the monomers is converted into a hydrocarbon soluble drying oil, onlybetween 0.1 to 5% by weight of the monomers is converted into a cyclicdimer. and 0-0.5% to an insoluble polymer, releasing pressure from thereaction zone, removing unpolymerized monomers and the cyclic dimer fromthe polymerized reaction mixture, and recovering said drying oil as asolution in said hydrocarbon diluent, the improvement which comprisescontinually flushing the entire interior surfaces of the gas space abovethe liquid level of the reaction zone with at least a portion of theliquid phase.

' ANTHONY H. GLEASON. I

STANLEY E. JAROS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

1. IN A SELECTIVE POLYMERIZATION PROCESS FOR PREPARING DRYING OILSWHEREIN A CONJUGATED DIOLEFIN HAVING 4 TO 6 CARBON ATOMS PER MOLLECULEIS HEATED IN THE LIQUID PHASE IN A REACTION ZONE AT A TEMPERATUREBETWEEN 50 AND 150* C., UNDER SUPERATMOSPHERIC PRESSURE AND IN THEPRESENCE OF A HYDROCARBON SOLUBLE PEROXIDE CATALYST FOR A PERIODSUFFICIENT TO CONVERT NOT MORE THAN 80% OF THE DIOLEFIN INTO A LINEAROILY POLYMER AND NOT MORE THAN 5% INTO A DIOLEFIN DIMER, THE METHOD OFREDUCING THE FORMATION OF SOLID INSOLUBLE POLYMER WHICH COMPRISESCONTINUALLY FLUSHING THE ENTRIE INTERIOR SURFACES OF THE GAS SPACE ABOVETHE LIQUID LEVEL OF THE REACTION ZONE WITH AT LEAST A PORTION OF THELIQUID PHASE.